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Electric fluctuations

November 06, 2012

Electric fluctuations

When weakly electric fish were discovered, scientists first thought their electric organs were defective

When weakly electric fish were discovered, scientists first thought their electric organs were defective. Their voltage, which is what electric eels, their better-known kin, use to stun and kill their prey, was too weak for hunting. Research eventually showed weakly electric fish use their signals to communicate, recognize gender, locate prey and even to navigate. It's a fishy equivalent of echolocation.

Sophie Picq, a master's student at McGill University, discovered that one electric fish, Brachyhypopomus occidentalis, is diverging in both the shape of their electric signals and in their DNA in different isolated populations across Panama.

“What we don't know is why,” says Alex Tran, a STRI fellow also from McGill. Is it genetic drift or is a selection agent acting upon these populations? Alex says the agent might be predation. Evidence shows that B. occidentalis populations could be modifying their signals to reduce detection from electroreceptive predators. “I expect that signals from electric fish that co-evolved with predators will be harder to detect than those from fish that never were in contact with predators,” he says.

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